1. Field of the Invention
The present invention relates to a liquid crystal projector.
2. Description of the Prior Art
In liquid crystal projectors, a liquid crystal panel, a light source lamp for backlight arranged on a rear surface of the liquid crystal panel, a signal processing circuit, and a power supply circuit are provided in a casing. Conventionally in the liquid crystal projectors, air cooling is performed by a cooling fan in order to restrain the rise in the temperature in the casing. Further, techniques for controlling the number of revolutions of the cooling fan have been developed on the basis of the temperature detected by a temperature sensor arranged in the casing in order to save energy and reduce noise by the cooing fan.
In methods of controlling the number of revolutions of the cooling fan on the basis of only the detected temperature, however, the cooling efficiency by the cooling fan is lowered in areas where air density is low, such as areas where air pressure is low, for example, highlands.
Liquid crystal projectors so adapted that two types of control tables for flatlands and highlands are prepared as a control table representing the relationship between a temperature and a control value of a cooling fan, and a user performs setting as to which of the control tables should be used have been developed. In such a liquid crystal projector, however, it is necessary for a user to perform a setting operation depending on an area where the liquid crystal projector is employed.